As is known, side doors of motor vehicles generally comprise a supporting framework, which defines, at the top, a window opening closed by a mobile window, when the latter is raised, and, at the bottom, a box-type body, which is open towards the window opening itself and is delimited by an inner wall, facing the inside of the passenger compartment of the motor vehicle, and by an opposite outer wall.
In particular, the inner and outer walls are fixed in a conventional way to the framework of the door, which is consequently set between said walls.
The box-type body delimits a compartment, in which there are usually housed the window, when the latter is lowered, and various components, such as, for example, a lock for closing the door, a key assembly and a window-regulator device.
Normally, the key assembly comprises a casing, basically shaped like a cylindrical cup and fixed to the outer wall of the box-type body of the door, and a key unit, which is also cylindrical, is engaged in an axially fixed position within the casing, is operatively connected to the lock by means of a tie rod or another transmission element, and can be displaced angularly with respect to the casing itself by means of a control key for disabling or enabling opening of the lock from the outside of the motor vehicle (safety function activated and safety function deactivated, respectively).
In particular, the key unit carries a plurality of engagement elements, which are normally pushed by respective springs in a position for coupling with a radial groove of the casing so causing the key unit and the casing itself to be angularly fixed to one another, and can be selectively uncoupled from the aforesaid grooves as a result of the interaction with the external profile of the control key.
The casing is prismatically coupled within a shaped through opening, which is made in the outer wall of the door and has a O-shaped profile, i.e., a profile formed by a portion shaped like an arc of circumference, the opposite ends of which are joined together by a rectilinear stretch.
The casing is moreover provided with an end annular flange, which is set, in use, bearing upon the outer wall of the door in a position corresponding to the inside of the opening and is designed to be fixed axially by means of a U-shaped clip, which is mounted on the side surface of the casing itself and co-operates bearing upon the outer wall of the door on the opposite side of the flange.
Key assemblies of the type described are relatively exposed to breaking. In fact, it is possible, with a screw driver or an elongated implement, to force the key unit to rotate rigidly together with the casing about its own axis, deforming or damaging the outer wall of the door, which is generally of reduced thickness, in an area surrounding the shaped opening, and to obtain deactivation of the safety function of the lock.
Furthermore, since the casing of the key assembly is fixed to the door from the outside of the motor vehicle, it is also possible to insert a screw driver or other similar implements between the end flange of the casing and the outer wall of the box-type body so as to extract the key assembly partially from its seat and thus gain access to the transmission element connecting the key assembly itself to the lock, so deactivating the safety function.